Automatic clamp for paper cutting machines



Feb. 5, 1935. J. F. SCHROETER 51'' AL 1,990,392

- AUTOMATIC CLAMP FOR PAPER-QUTTING MACHINES 5' Sheets-Sheet l Filed Jan. 28, 1933 Gttornp 1935- J. F. SCHROETER ET AL 1,990,392

AUTOMATIC CLAMP FOR PAPER CUTTING MACHINES Filed Jan. 28, 1953 5 Sheets-Sheet 2 1 31 I nentor JR Jcraeier Bg .lfazworz/ (Utorucg '-Feb. 5, 1935. J. F. SCHROETER ET AL 1,990,392

AUTOMATIC CLAMP FOR PAPER CUTTING MACHINES Filed Jan. 28, 1933 5 Sheets-Sheet 3 3nventors dfls'c/zroeir JAHWM (lttomeg Feb. 5, 1935. J. F. SCHROETER El AL 1,990,392

AUTOMATIC CLAMP FOR PAPER CUTTING MACHINES Filed'Jan. 28, 1935 5 Sheets-Sheet 4 Y R lhwentons cZZTJc/uwdr B 61A. man

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(Ittorneg Feb. 5, 1935. i J. F. SCHROETER El AL 1,990,392

AUTOMA' IIC CLAMP FOR PAPER CUTTING MACHINES Filed Jan. 28, 1955 5 Sheets-Sheet 5 I i WT I, l a; I 'iaa'i ll r l g L- J7 l 561 i: .1

U-r-fi I 37 4V I 1 I 629 g 1 60. 35 I 54 3nventors attorney Patented Feb. 5, 1935 1 UNITED STATES PATENT OFFICE AUTOMATIC CLAMP FOR PAPER CUTTING MACHINES John F. Schroeter, Atlanta, and John A. Hanson, College Park, Ga.

Application January 28, 1933, Serial No. 654,048 11- Claims. (Cl. 164-51) This invention relates to automatic clamps for cutting machines and, among other objects, aims to provide greatly improved mechanism for actuating a clamp to apply uniform clamping pressure to the work in the form of piles of sheets or the like of different thicknesses. The main idea is to provide a relatively simple, eificient and dependable attachment to apply uniform clamping pressure to piles of sheets of any thickness up to the capacity of the machine without being influenced by temperature, humidity, the time during which the machine is used or ordinary wear of the parts. Another'important aim is to reduce to a minimum the power required to operate the clamping mechanism. A still further aim is to provide clamping mechanism which, not only effectively clamps the work during the cutting stroke of the knife, but also holds the work clamped until the knife has reached the upper limit of its return stroke, to prevent any disturbance of the stock, such as narrow strips of paper and small labels.

Other aims and advantages of the invention will appear in the specification, when considered in connection with the accompanying drawings, wherein:

Fig. l is a front elevation of a paper cutting machine having the preferred form of clamping machine applied thereto;

Fig. 2 is a vertical sectional view of the machine taken on the line 2-2 of Fig. 1;

Fig. 3 is a sectional view on an enlarged scale, taken on the line 3--3 of Fig. 1, and showing the position of the operating parts when the clamp is released and at the top of its travel;

Fig.

the position of the parts after clamping pressure is applied;

Fig. 5 is a fragmentary top plan view of the operating mechanism;

Fig. 6 is a sectional view, taken on the line 6-6 of Fig. 3; and

Fig. 7 is a sectional view taken on the line- 7-7 of Fig. 3.

Heretofore, the automatic clamping mechanisms for paper cutters have been unsatisfactory in many respects. Some of them which embody friction clutches are subject to destructive wear and are not capable of applying uniform clamping pressure. weather conditions and their efficiency diminishes when they are used for long periods. The ordinary spring devices are incapable of applying uniform clamping pressure to piles of different thicknesses and require considerable power 'rying a work table 4 is a view similar to Fig. 3 but showing 'lhey aid affected by changes 'inthroughout the cutting cycle. Moreover, there are no automatic clamps of which we are aware capable of holding the work clamped until the knife reaches the upper limit of its stroke. It is important that the clamping mechanism shall be capable of exerting a predetermined clamping pressure on the work under all operating conditions, such as changes in temperature, changes in humidity, and duration of continuous operation. This invention contrives to meet these requirements and to eliminate the aforesaid drawbacks.

Referring particularly to the drawings, the illustrated mechanism is shown as being applied to an ordinary automatic paper cutting machine of the well known draw-cut type. However, the invention is not limited to use on such machines, the mechanism being contrived to apply as an attachment for many different designs of machines.

In Figs. 1 and 2, the machine is shown as having the usual base 10 and a metal housing 11 car- 12. A reciprocating cutter bar 13 and an ordinary clamp 14 are guided in the upper part of the housing above the work table. The cutter is actuated by the usual power-driven crank-shaft l5 and pull-rods 16 connected to the opposite ends of the cutter bar. In this example, the power is adapted to be delivered by a beltdriven pulley 1'1.

The clamp 14 is here shown as being connected at its ends to pull-bars 18. These pull bars have shouldered stud pins 19 at their lower ends which project through pivoted slotted links 20 connected to clamp arms 21 on a clamp-operating shaft 22. The slotted links which are pivoted on the clamp-operating arms permit manual lowering of the clamp by means of a treadle 23 having a slotted link 24 pivotally connected to an arm 25 on one of the pull-bars which projects forwardly through an opening in the base portion of the housing. The slotted. arm connection of the treadle permits the treadle to be tilted upwardly against the housing when the clamp is poweroperated,

In this instance, the clamp is raised automatically by an ordinary torsion spring 26 on a shaft 2'7 carrying a pair of segmentalwheels 28 on which clamp-lifting chains 29 are connected.

The mechanism thus less conventional. It has long since been common practice to transmit clamping pressure from the a crank-shaft through the clamp shaft of this type of machine. The present mechanism constitutes an attachment designed to far described is more or displace old types of clamp-operating mechanism connected to these shafts.

Referring to Figs. 3 and 4, the clamp-operating mechanism is shown as being actuated by an ordinary eccentric 30 on shaft 15 having a connecting rod 31 connected to a cam 32 loosely mounted on the clamp-operating shaft 22, the arrangement being such that the cam is oscillated on the shaft and has provision for imparting actuating movement to saidshaft. This cam has an arcuate cam surface 33 concentric with the axis of shaft 22 and also a cam slot 34 at the rear end of the arcuate portion.

A fulcrum arm 35 is shown as being keyed on the shaft 22 adjacent to the cam 32 and the cam is designed to impart actuating movement to the shaft through this arm. For this purpose the end of the fulcrum arm carries a rotatable stub shaft 36 on which is keyed a compound lever 37.carrying at its inner end on a stub 38 a cam roller 39 adapted to engage the cam surface 33 and cam slot 34. To the outer end of the compound lever is pivotally connected on a pin 40 a toggle link 41 projecting toward the front of the machine. Another toggle link 42 is pivotally connected at its rear end to link 41 and at its front end to a floating arm 43 loosely mounted on the hub of the fulcrum arm 35 to oscillate about the shaft 22. The floating arm has a pivot pin 44 for the link 42 and this pin also carries a ratchet pawl 45 projecting rearwardly below the toggle joint and shown as having a plurality of ratchet teeth which engage an internal ratchet segment 46 carried by a web 47 which is also loosely mounted to oscillate on the shaft 22-on the opposite side of the cam 32 from the fulcrum. arm.

Referring to Figs. 3, 4 and 7, the forward end of the ratchet segment 46 is shown as being bifurcated and has an eye carrying a pin 48 to which is pivotally connected an eye 49 on the forward end of a spring-compression bolt 50.

which projects rearwardly between upstanding stop shoulders 51 on a bracket 52. Herein, the rear faces of the shoulders act as abutments for a pair of compression springs 53 confined between them and a follower plate 54 adjustably mounted on the rear end of the bolt by an adjusting nut 55. The arrangement is such that when the ratchet 46 is moved forwardly by the pawl 45, the springs are compressed and their pressure is multiplied and transmitted through the mechanism to the clamp.

In Fig. 3, the parts are shown in their relative positions when the clamp is at the top of its stroke. The pawl 45 is free to click or ride upwardly on the ratchet 46. The shaft 22 and its connected parts in these relative positions are oscillated rearwardly by the eccentric until the clamp contacts with the work. That is to say, the spring action is not brought into play until after the Work, of whatever pile thickness, is engaged by the clamp.

Now, the mechanism on its rearward stroke must overcome the torsion clamp-lifting spring 26'by virtue of the interlocking engagement between the cam roller 39 and the cam notch 34. For this purpose, the compound lever 37, the floating arm 43 and other connected parts are normally held by spring pressure in the positions shown in Fig. 3. In this instance, the hub of the floating arm 43 has a segmental gear 56 whose teeth mesh with a segmental pinion 57 on a spring lever 58 pivoted between its ends on apivot pin 59 carried by a projecting crank arm 60 integral with the fulcrum arm 35. The free end of the spring lever is shown in Fig. 3 as having a saddle 61 for a ball or roller 62 acting as a thrust abutment for a compression spring 63 on a spring rod 64. The upper end of the rod 64 projects freely through the ball or roller 62 and the saddle 61 so that the spring may be compressed by the action of the segmental gears 56-57. The normal compression of the spring is adjusted by an adjusting nut 65 threaded on the rod and the lower end of they rod has an eye 66 connected to a pivot pin 67 on a crank arm 68 keyed to compound lever shaft 36. The spring thus exerts pressure through the rod 64 on the crank arm 68 and tends to rotate the compound lever counterclockwise, thereby normally holding the roller 39 in the cam slot 34.

The compound lever 37 is restrained from moving counterclockwise out of the cam slot by an adjustable stop screw 69 extending through an ear 70 integral with the floating arm '43. This stop screw is adjusted to engage the front side of the fulcrum arm 35, thereby preventing these two arms from closing together. The toggle links 41 and 42 on the arms prevent the compound lever. from moving farther in a counterclockwise direction. Moreover, the toggle arms are pre-' vented from moving outwardly at their joint and forcing the pawl 45 into locking engagement with the internal ratchet 46 until the compound lever moves in a clockwise direction.

Assuming that a pile of paper is in the machine, all of the movable clamping mechanism on the shaft 22 is actuated-as a rigid unit by the eccentric 30' until the clamp engages and initially clamps the pile, it being understood that the pawl 45 clicks or rides rearwardly over the internal ratchet 46 during this initial clamping movement. When the clamp initially clamps the work, the fulcrum arm 35'and clamp-operating shaft 22 both stop; but the cam 32 continues to rotate rearwardly or counterclockwise as viewed in Fig. 3. The continued movement of the cam forces the compound lever 37 to swing clockwise on the axis of stub-shaft 36 as a fulcrum or center until the cam slot 34 passes the cam roller 39. By virtue of this swinging movement of the compound lever, the toggle links 41-42 move outwardly at their joint and a heel 71 on the link 42 engages the back end of the pawl 45 forcing it into locking mesh with the internal ratchet 46. After the pawl is thus locked on the ratchet,

further swinging movement of the. compound lever forces the floating arm 43 forwardly by the toggle links 41-42, thus further separating the floating arm from the fulcrum arm 35 and compressing the spring 63 by the action of the segmental gears 56-57 until the cam roller 39 emerges from its slot 34 and rides on the arcuate surface 33 of the cam 32. While the compound lever 37 is swinging in a clockwise direction and imparts the separating movement to the floating arm 43, the floating arm imparts a corresponding forward movement to the internal ratchet 46. The extent of this movement is predetermined by the design of the parts. In an ordinary paper cutting machine, it is contemplated that, it will not be more than two inches. This movement compresses the springs 53 through the compres sion bolt 50. After this action takes place, the maximum clamping pressure is applied to the paper clamp and the cam roller 39 rides on the arcuate surface 33 of the cam. Thus, the springs 53 exert all of the clamping pressure on the work before the knife contacts with the work.

Referring to Fig. 4, the final spring clamping pressure has been applied and the cutting knife has completed its cutting stroke. The cam 32 has reached the rearward end of its swinging stroke and is about to start forward. No power is expended in holding the clamp on the work while the roller 39 is riding on the cam face 33. The clamping pressure on the pile will not be released until the cam notch 34 again reaches the cam roller 39 and the roller seats itself therein. As the roller seats itself, the outer end of the compound lever 3'7 swings counterclockwise and this movement straightens out the toggle links 41-42, thereby releasing the pressure of the heel '71 on the pawl 45.

It will be noted that the forward toggle link 42 carries a pivoted latch 72 having a catch 73 extending through a slot '74 in the ratchet pawl 45 and also a slot '75 in the link 42. This latch is spring-urged into engagement with the lower edge of the pawl by means of a compression spring '76. This arrangement enables the straightening movement or disengaging movement of the toggle links to release the ratchet pawl from the internal ratchet 46. As soon as the pawl is thus released, the compression springs 53 force the internal ratchet back to its normal position of rest, ready for the next cutting cycle.

When the cam slot 34, the fulcrum arm 35 and the floating arm 43, as well as the other connected parts, assume the positions shown in Fig. 3, as the cam reaches the extreme end of its forward movement, the latch '72 is trippedby an adjustable trip or stop 7'7 secured in the bifurcated forward end of the internal ratchet 46. ,The catch strikes this stop and again releases the pawl, so that it is free to engage the internal ratchet 46 and ride backwardly on its teeth. The latch has just been disengaged in Fig. 3.

The arrangement of the parts is such that the cutter bar reaches the top of its stroke as the latch 72 releases the ratchet pawl 45. The clamp is not released or permitted to be raised until the cam roller 39 is seated in its cam slot. Then, the torsion lifting spring can raise the clamp as the cutter bar rises in advance of the clamp to the upper limit of its stroke. It is quite important that the clamp hold the work while the cutter knife rises to clear it; otherwise, the risingknife will disturb the sheets in the released pile.

It will be further observed that the spring pressure exerted on the clamp is greatly multiplied through the mechanism. The mechanical advantage is measured by the ratio between the radius of the segmental ratchet and the radius of the clamp arms 21, the intermediate parts being relatively immovable until the compression springs 53 arereleased. Hence, ordinary compression springs may be used to exert pressure of considerable tonnage.

Obviously, the present invention is not restricted to the particular embodiment thereof herein shown and described. Moreover, it is not indispensable that all the features of the invention be used conjointly, since they may be employed advantageously in various combinations and subcombinations.

What we claim is:

1. In a power-driven cutter of the character described having a reciprocating knife and clamp, automatic clamp actuating mechanism having positively driven means connected initially to lower the clamp into contact with material of "different thicknesses and to apply substantially uniform initial clamping pressure thereto;

and spring resistant mechanism associated with said positively driven means and rendered 0perable incident to the application of initial contacting pressure of said clamp on the material to apply a predetermined final clamping pressure to the material before the knife engages it.

2. In a power-driven cutter of the character described having a reciprocating knife and clamp, automatic power driven clamp actuating mechanism having positive driving means con.- nected initially to lower the clamp into contact with material of different thicknesses and to apply substantially uniform initial clamping pressure thereto; normally mechanism associated with said positively driven means and rendered operable incident to the application of initial contacting pressure of said clamp to apply a predetermined final clamping pressure to the material before the knife engages ratchet operated means assoit; and pawl and ciated with said spring resistant mechanism to maintain the clamping pressure on the material until the knife clears the material on its upward 'stroke.

3. In a, power-driven paper cutter of the class described, automatic clamping means connected to be operated by the cutter crank-shaft, comprising a clamp-operating shaft having crank arms connected to the clamp; a cam rotatably mounted on the clamp-operating shaft; an eccentric on the cutter crank-shaft connected to oscillate the cam; an arm fixed on the clampoperating shaft adjacent to the cam; a springurged member on said arm engaging the cam and connected to transmit initial ment from the cam to the arm; normally inactive compression springs adjacent to the clampoperating mechanism; and means operable by initial clamping pressure to effect operating engagement between the compression springs and said mechanism, whereby the compression springs exert final clamping pressure to the clamp as the cam continues to move on its clamping and return strokes.

4. In a power-driven paper cutter of the class described, automatic clamping means connected to be operated by the cutter crank-shaft, comprising a clamp-operating shaft having crank arms connected tothe clamp; a cam rotatably mounted on the clamp-operating shaft; an eccentric on the cutter crank-shaft connected to oscillate the cam; an arm fixed on the clampoperating shaft adjacent to the cam; a springurged member on said arm engaging the cam and connected to transmit initial clamping movement from the cam to the arm; normally inactive compression springs adjacent to the clamp-operating mechanism; a segmental internal ratchet connected to the compression springs; a ratchet pawl cooperating with said segmental ratchet and connected to said mechanism; and means to lock said pawl in engagement with said segmental ratchet incident to the application of initial clamping pressure exerted by the cam.

5. In a power-driven paper cutter of the class described, automatic clamping means connected to be operated by the cutter crank-shaft, comprising a clamp-operating shaft having crank arms connected to the clamp; freely rotatable on said clamp-operating shaft and having an arcuate surface with a cam notch in one end portion; a fulcrum arm keyed on the clamp-operating shaft adjacent to the cam; a

compound lever pivotally mounted between its idle spring resistant clamping movea segmental cam F ends on the end of said fulcrum lever; a cam roller on one end of the compound lever normally resting in said cam notch; toggle links connected at one end to the other end of the compound lever; a floating arm also freely rotatable on said clamp-operating shaft and connected to the opposite end of the toggle links; a compression spring normally holding said cam roller in said cam notch whereby the cam may impart movement to all of said parts simultaneously until the clamp makes contact with a pile of sheets of any thickness up to the capacity ratchet pawl pivoted on said floating arm lying below said toggle links; a plurality of.compression springs mounted on the machine; a ratchet connected at one end to compress said springs and oscillatably mounted on said clamp-operating shaft, said ratchet being engageable by said pawl; said cam, as it continues to move on said clampoperating shaft after the clamp makes contact, making the compound lever with its toggle links and ratchetpawl connection operative to engage and lock the pawl on the ratchet and to move the ratchet having the compression springs connected thereto so as to cause the springs to exert the required pressure through said mechanism to the clamp; and said cam being effective to maintain the clamping pressure until the knife has made its cutting stroke and returned to its upper position.

6. In the clamp-operating mechanism set forth in claim 5, a spring-urged latch carried by one of said toggle links to engage and hold the said ratchet pawl out of engagement with the ratchet, said latch permitting the clamping of piles of different thickness and the free return of the clamp to its highest position after the clamping operation; said latch having a trip secured to said ratchet so as to be released when the clamp is at the highest point of its travel and being free to contact with the ratchet so as to perform successive cutting operations on piles of different thicknesses without any adjustment.

7. In a paper cutting machine of the class described, automatic clamping mechanism comprising direct power driven means connected initially to lower the clamp to engage a pile of sheets and adapted to be released from the clamp operating means; spring means of a predetermined strength associated through the mechanism to connected automatically to engage the pawl with the ratchet only when the clamp has initially applied a predetermined pressure to the pile and the direct power-driving connections are simultaneously released, whereby the spring means furnishes all of the energy required to hold the work clamped without requiring any motive power for the clamp during the cutting operation.

8. In a power-driven cutting machine having a reciprocating cutter and clamp, automatic clamp operating mechanism comprising positive power driven means connected initially to move the clamp into engagement with k to be cut and adapted to be released from the clamp operating means; springs associated with the mechanism having a predetermined and adjustable compression strength; cam operated means including a compound lever connected automatically to relieve the power driving means of the initial clamping load and simultaneously transfer all of the load to said springs, thereby the material driving means; an arm keyed to said shaft ad-' jacent to the cam; a spring-urged compound lever pivoted on the arm and having one end engaging the cam and arranged to impart initial clamping movement to the shaft as the cam oscillates in one direction; a floating arm rotatably mounted on the shaft. and carrying a ratchet pawl at its outer end; toggle links connecting the other end of said compound lever to said floating arm so as to actuate the pawl incident to pivotal movement imparted to the compound lever by the cam; a spring-loaded ratchet adapted to be engaged by the pawl; means on the toggle link connections to force the pawl into operative engagement with the ratchet as the cam imparts initial pivotal movement to the compound lever after the clamp comes to rest on the material; and latch and trip means connected to control the action of the pawl, the arrangement being such that said cam servesto transfer all of the clamping load to the spring-loaded ratchet after the clamp comes to rest on a pile of any thickness within the capacity of the machine and to main tain the spring pressure throughout the cutting cycle, while all of the power applied is available to operate the cutter mechanism.

10. ha power driven paper cutter or the like, automatic clamp operating means including mechanism initially to lower the clamp into engagement with the work and adapted to be automatically released from operating engagement with the clamp; normally idle springs of a predetermined strength associated with said mechanism; means simultaneously and -automatically connecting the mechanism to the springs when the clamp engages the work whereby the power driving means actuates the springs; and lever means in said mechanism connecting the springs to operate the clamp and multiplying the power delivered thereto by the springs.

11. In a cutting machine of the character described having a power driven cutter and a clamp, automatic clamp operating mechanism comprising positively driven means connected to the clamp to apply a predetermined pressure to. the material to be cut, irrespective of itsthickness, before the cutting said mechanism in cluding means initially to impart work engaging movement to the clamp before the spring pressure is applied and, finally, to impart the spring pressure to the clamp; means connected automatically to release the power driving means from the'clamp after the pressure is applied so that all of the power is available to perform the cutting operation; and means automatically to release the spring clamping pres-- knife completes its cutting sure after the cutting cycle, whereby the machine may be operated successively to out piles of different thicknesses without any adjustment. I

' JOHN F; SCHROETER.

JOHN A. HANSON.

knife engages the material;' 

